From here, follow the aisles to make your way towards the back of the store. There will Pikachu and Merryl plushies floating around on a display. Whip out your Poke Finder and take a picture of Gengar.

You’ll find what appears to be Acerola at the back of store and she will try to convince you to stop your trial. Refuse to leave! Eventually, the apparition will go away and you can head into the backroom where you will find TotemMimikyu.